Toona sinensis is a Meliaceae defolite arbor, and its leaves can be used in food and show the medicinal functions on antiphlogosis, detoxification, disinfestations and the treatments on enteritis, dysentery, carbuncle, scabies, tinea capitis, and the improvements on somatoplasm. In the folk healing in China, the root skin of T. sinensis can be used to treat leucorrhoea, rheumatism, and gastrointestinal disorders, and the water with leaves can wash away tinea. T. sinensis further shows functions on prevention of cold and enteritis.
Chen et al. (2009) indicated that gallic acid extracted from the leaves of T. sinensis has the reactive oxygen species (ROS)-mediated anti-tumor activity on prostate cancer, and the extraction of T. sinensis leaves is made by boiling T. sinensis leaves in the water, filtering through sieves, lyophilizing and extracting with ethanol with various concentrations and the lyophilization treatments to obtain different extracts (Chang et al., 2006; Wang et al., 2008). In addition, U.S. Patent Publication No. 2009/0169658 A1 also indicated that the extract is afforded by the water extraction on T. sinensis leaves and the alcohol processed water extract is further obtained using liquid chromatography with reverse column and is used to inhibit the proliferation of cancer cells. Some food advertisements exaggerate that the T. sinensis tea brewed with hot water on the T. sinensis tea bags has the anti-tumor effect. However, the temperature, vapor and pressure of hot water are not sufficient to leach the components of T. sinensis into the water, and the dosages of components also do not achieve the therapeutic dosage and the therapeutic concentration.
Water and various organic solvents have different polarities, and the extraction uses the strength/weakness of the distribution coefficients of chemicals to the organic solvents to obtain the target extract. Furthermore, partial extracts might be destroyed or lost by the water-boiling extraction or the organic-solvent extraction, which thus results in the decrease of yield and recovery. The remaining organic solvent in the extracts also might harm the users. Therefore, finding the extraction method with advantages of non-toxicity and non-residue and without decrease of yield/recovery becomes the target in the application of T. sinensis. 
Obesity, diabetes mellitus and their derived metabolic diseases are the interesting issues along with the human culture progress, and obesity is the main reason for the diseases such as cardiovascular disease, insulin resistance, diabetes mellitus and cancer, etc. The currently effective manner to decrease blood glucose is the subcutaneous injection of insulin. However, it needs to tightly monitor blood glucose and adjust insulin dosage, and thus it makes the diabetes patients' lives inconvenient. Type II diabetes mainly is treated with oral hypoglycemic agents, which mainly includes four groups, insulin-secreting agents (sulfonylureas and glinides), Metformin, insulin sensitizer (such as thiazolidinedion (TZD)) and α-glucosidase inhibitor. The functional mechanism and side effects in each group are not the same, and patients must try several drugs to find out the sufficient and effective drugs.
Since some oral hypoglycemic agents would induce gastrointestinal side effects such as diarrhea to result in patients' repulsion, they cannot be taken by the patients with liver or kidney disfunction. Further, rosiglitazone of the insulin sensitizer-typed drugs has hazard on increasing myocardial infarction and fracture in women. Therefore, hypoglycemic agents with more efficiency, less side effects, lower price and beneficial on liver- or kidney-disfunctioned patients still have necessity in the international medicinal market.
Although there are various natural plant extracts in the market announced to loss weight or reduce blood glucose, the scientific evidences are absent and these extracts cannot be acceptable by the clinical doctors and the international market. Accordingly, the purposes of the present invention is to overcome the drawbacks in the conventional extraction method, efficiently prepare the extracts on anti-diabetes and anti-metabolic diseases.
It is therefore attempted by the applicant to deal with the above situation encountered in the prior art.